How to use AP Style commas after dates

Question

I was wondering how you are supposed to use commas after full dates in AP style. I've been told to always put a comma after the year, like in the sentence:

On April 4th, 2012, I found a cat.

However, I thought the following might be an exception:

April 4th, 2012 brought the death of my cat.

Notice how there's no comma after "2012." My teacher disagreed and told me that the AP style dictates that we always put commas after dates like that.

The way I reasoned through it is by replacing the dates with the word "Monday"

On Monday, I found a cat.

Monday brought the death of my cat.

And you wouldn't write

Monday, brought the death of my cat.

TL;DR

Which one is correct?

April 4th, 2012 brought the death of my cat.

or

April 4th, 2012, brought the death of my cat.

Answer 1

Unless your instructor can cite chapter and verse of the AP Stylebook, consider it a rumor. Anyone who can claim total knowledge of a 400 page document with 200+ changes in the last year alone is probably lying or at best mistaken.

Your reasoning is sound, but I don't have access to the latest Stylebook.

Answer 2

As msw says, it's probably rumor.

I would leave the comma in after 2012 because the sentence

April 4th, 2012 brought the death of my cat.

has an extra bit of white space before the year, and no extra space following it. This optically brings the year closer to the word "brought" than to the word "4th", which goes against all visual sense. (In my mind.)

Additionally, one could read (admittedly I am going out on a long limb here) that on April 4th your cat's demise was brought about by the machinations of the devilish year, 2012.

As one of the Fowlers probably would have put it, this sentence needs recasting. But then again they weren't American newspapermen.

Answer 3

I'm sure that we used to always put the comma after the year; however, I'm seeing the comma omitted most of the time nowadays, so maybe the rule has changed.

I do have one suggestion, though. Please write the date April 4, 2012 and NOT April 4th, 2012. I know that the latter is never correct!